On the pro side, I would say that this measure is relatively simple to administer.
In terms of disadvantages, however, since the benefits are not directly related to the level of earned income, and therefore are not modelled on earned income, it may be much more attractive for some individuals to remain on CERB for as long or as often as possible rather than work.
For example, people receiving minimum wage and working less than 35 or 40 hours may earn more by receiving the CERB than by working. This is a significant disincentive to work. This is the biggest disadvantage.